Fierce Rivals: When Khorne’s Greater Daemons gather for war, there is only rivalry and hostility between them.
After a model from this battalion has fought in the combat phase
for the first time, you can pick another model from the same battalion that has not yet fought in that combat phase and is within 3" of any enemy units. That model fights immediately, before the opposing player picks a unit to fight in that combat phase. That model cannot fight again in that combat phase unless an ability or spell allows it to fight more than once.